In order to prevent destruction due to an overcurrent, a semiconductor device is provided with a sense region for sensing a current that flows through the semiconductor device. Japanese Patent Application Publication No. H7-245394 (patent document 1) discloses a semiconductor device provided with a main region in which an IGBT is formed and a sense region for sensing a current that flows through the main region, wherein the main region and the sense region are formed on a same semiconductor substrate. An IGBT similar to that of the main region is built into the sense region, and the sense region and the main region are arranged separated from each other by 100 μm or more. Accordingly, carrier interference in a boundary region between the sense region and the main region is prevented, and a current ratio of a main current that flows through the main region to a sense current that flows through the sense region is kept approximately constant.    Patent Document 1: Japanese Patent Application Publication No. H7-245394